The discussion in the previous section deals with cluster states composed of qubits, which can include qubits encoded in bosonic modes.
This two-layer encoding can be seen as a bosonic code concatenated with a topological code, a subject of growing interest [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}.
The main motivation here is that CV errors larger than those the inner bosonic code can handle are picked up and corrected by the outer qubit code.
